This invention relates generally to an inserted blade rotary cutter for the traced rough turning of rods, pipes and the like workpieces; the cutter being of the type which has a rotary base plate with a plurality of sliders arranged thereon for movement in the radial direction and each supporting on its end facing the center of the plate a blade holder.
In the traced preturning of rods, tubes and the like, it is desirable to remove only the marginal decarbonized layer and the scales and not--as it is otherwise usual in the preturning operation,--also to improve the concentricity and uniformity of the diameter of the workpiece under the preturning process. In addition, it is required to operate at as low cutting losses as possible. At the same time, the entire jacket surface of the workpiece has to be flawlessly milled off. The above requirements are attained by reducing the diameter of the processed workpiece by removing an outer layer which has a constant thickness. In the case when a workpiece having an oval cross section is being processed, the cutting blade during each revolution of the head performs a back-and-forth movement in radial direction.
From the British specification No. 1,479,872 a cutter head for the traced rough turning is known in which the blade holders are guided by sliders supported for movement in radial guideways in order to follow a non-circular contour of the processed workpiece. Since in this known design the blade holder has to be radially displaced under the cutting pressure excessive frictional forces result and these forces have to be overcome by springs arranged between the sliders and the assigned blade holder. The forces employed for displacing the blade holder in the slider act also partially against tracing means which roll on the periphery of the processed workpiece and consequently excessive wear of this tracing means takes place. In this known design the blades together with the blade holders can follow the contour of the workpieces only with difficulties and this fact especially at high rotational speeds of the cutter head is disadvantageous.